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Home arrow Nutrition arrow Intermittent Fasting arrow Do Pre-Workout Supplements Break a Fast? Interesting Facts

Do Pre-Workout Supplements Break a Fast? Interesting Facts

Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 22, 2023
3 min read 1417 Views 0 Comments
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Pre-workout supplements are a popular choice for those looking to enhance their athletic performance and energy levels. But do pre-workout supplements break a fast?

does pre-workout break a fast

Intermittent fasting and a solid exercise routine go hand in hand. For many people who are serious about working out, a pre-workout supplement is their usual go-to before hitting the gym.

But what about during your fasting period? Many people have a fasting window from 12 to 16 to 18 hours! That’s a lot of time to fit in a workout.

Does pre-workout break your fast? Our experts have come to answer all your burning questions about intermittent fasting protocols and pre-workout supplements.

Does Pre-Workout Break a Fast?

If you’re looking to add some pre-workout supplements to your daily exercise routine but still want to follow intermittent fasting, you’ll be happy to know that pre-workout supplements do not break your fast.

Pre-workouts don’t engage your GI tract, and they don’t have any significant calories, nor do they cause an insulin response.

Does L-Citrulline Break a Fast?

If your L-Citrulline supplement does not have any added sugars, it will not break your fast.

L-Citrulline is one of the non-essential amino acids. It’s produced naturally by the body and found naturally in some foods, like watermelon.

Does Creatine Break a Fast?

Creatine is calorie-free and does not spike your insulin levels. If you’re fasting with a keto diet, creatine won’t break your fast or kick you out of ketosis.

However, it may slightly affect autophagy, so keep creatine to a minimum.

What Does Pre-Workout Do?

Pre-workout supplements are meant to give you energy during your exercise session. As the name suggests, these supplements are meant to be taken pre-workout. Their purpose is to help ease the exhaustion of an intense workout session.

Pre-workouts encourage muscle growth, reduce mental and muscle exhaustion, aid in muscle recovery, and even help build muscle mass and encourage better blood flow. They keep you focused and help improve your overall performance.

What’s Pre-Workout Made of?

Many pre-workout supplements are made of a variety of different ingredients. Let’s look at some of the most common pre-workout ingredients: caffeine, BCAAs, creatine, and beta-alanine.

Caffeine is by far the most common ingredient. Caffeine helps give you that boost of energy you need to make it through your workout, even if you don’t want to hit the gym that day.

BCAAs, or branched-chain amino acids, are another common ingredient. These help promote muscle growth and encourage better muscle recovery after your workout. They reduce the damage done to your muscles after a particularly intense workout session.

Creatine is another common ingredient in pre-workouts. When used in combination with other pre-workout ingredients, creatine gives your muscles energy, helps increase muscle endurance, and restores your ATP.

Finally, most pre-workout supplements are made with beta-alanine. This particular ingredient allows you to do very high-intensity workouts by reducing your recovery time, thus reducing your fatigue and helping buffer your muscles.

These Pre-Workout Ingredients Would Break a Fast

Not all pre-workout supplements are made the same. Some supplement companies add ingredients to their pre-workouts that wouldn’t be good for intermittent fasting.

Keep an eye out for these ingredients that would break your fast.

#1 Carbs in Any Form

When intermittent fasting, you want to stay away from carbs in any form: sugar, artificial sweeteners, or any other supplement that could be a carbohydrate.

If your pre-workout supplement contains any carbs, it will break your fast.

#2 Whey Protein

While whey protein has a lot of benefits for a pre-workout, you’ll want to avoid it if you’re taking it during your fasting period.

Like any other caloric beverage, whey protein increases your calorie intake and can break your fast.


BCAAs are amino acids, and they can break your fast depending on why you’re fasting. For the most part, BCAAs don’t induce a high enough insulin spike to consider breaking your fast.

However, if you’re a stickler for the rules and want to avoid all insulin increases, avoid pre-workouts with BCAAs.

Can I Take Pre-workout on Keto?

To stay in ketosis, you need to focus primarily on your carb intake. Protein is also another factor, but the only thing you need to be concerned with is carbs for pre-workout.

Not all pre-workouts are keto-friendly. But, there is no reason that you can’t take a pre-workout while on a ketogenic diet. Just make sure that whatever brand of pre-workout that you’re using is low in carbs.

Most pre-workouts are reasonably low in carbs or entirely carb-free.

A Word From Our RD

Pre-workouts are well known in the health and fitness industry. Most pre-workouts are great for athletic performance, help you keep up your energy levels, and point you toward your fitness goals.

Generally speaking, pre-workouts do not cause any sort of health problems. But, due to the amount of caffeine, you may experience increased blood pressure, stress, and difficulty sleeping. If so, make sure you stop and contact your certified medical professional.

Otherwise, you want to stick with a pre-workout blend that doesn’t use artificial sweeteners, sugar, or other carbs. You’ll be surprised by the mental focus and increased energy levels after your exercise routine is over.


So, is it true that pre-workout supplements break a fast? Our answer is a resounding: no! While not all pre-workout is made the same, if you’re aware of the ingredients and avoid supplements with many carbohydrates, sugars, or insulin spiking amino acids, you’ll be good to go.

For the most part, many manufacturers are aware that intermittent fasting and a good exercise routine go hand in hand.

This is why there are plenty of pre-workout blends made explicitly for those who need to be able to use them without breaking their fast.

Written by Thalia Oosthuizen
Thalia has always wanted to be a writer, starting her first local newspaper at the age of 11. She also has enjoyed a passion for health and fitness since a young age, playing many sports through her schooling career, and still enjoys biking, running, and swimming today. She studied English Language at University for 3 years, developing a passion for spelling, grammar, and research. She now has over 10 years of experience writing, proofreading, and editing, and has paired this with her love for health and fitness by writing health content.
The article was fact checked by Rosmy Barrios, MD
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Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 22, 2023
3 min read 1417 Views 0 Comments

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